Understanding the discharge current behavior in reactive high power impulse magnetron sputtering of oxides

Aiempanakit, Montri; Aijaz, Asim; Lundin, Daniel; Helmersson, Ulf; Kubart, Tomáš

doi:10.1063/1.4799199

Cited by 94 publications

(73 citation statements)

References 32 publications

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“…However, Aiempanakit et al [17] stated that the large discharge current in oxide mode are mainly attributed to the large ionic current due to the impingement of a high fraction of O 1+ ions. Hala et al [18] have shown a peak current dependency on the pulse frequency, in which a higher peak current was recorded at lower pulse frequency.…”

Section: Introductionmentioning

confidence: 99%

Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

Shimizu¹,

Villamayor²,

Lundin³

et al. 2016

J. Phys. D: Appl. Phys.

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Abstract.A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N 2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N 2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (111)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

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Section: Introductionmentioning

confidence: 99%

Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

Shimizu¹,

Villamayor²,

Lundin³

et al. 2016

J. Phys. D: Appl. Phys.

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“…Measured energies of reactive gas ions in HiPIMS discharges suggest that the ions originate from the target surface rather than from the gas phase. 20 It is therefore important to determine the partial sputtering yield of the reactive gas from the target surface to evaluate the contribution of sputtering to the total reactive gas ion flux.…”

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confidence: 99%

Evolution of sputtering target surface composition in reactive high power impulse magnetron sputtering

Kubart

Aijaz

2017

Journal of Applied Physics

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Evolution of sputtering target surface composition in reactive high power impulse magnetron sputtering. The interaction between pulsed plasmas and surfaces undergoing chemical changes complicates physics of reactive High Power Impulse Magnetron Sputtering (HiPIMS). In this study, we determine the dynamics of formation and removal of a compound on titanium surface from the evolution of discharge characteristics in argon atmosphere with nitrogen and oxygen. We show that the time response of a reactive process is dominated by surface processes. Thickness of the compound layer is several nm and its removal by sputtering requires ion fluence in the order of 10 16 cm -2 , much larger than the ion fluence in a single HiPIMS pulse. Formation of the nitride or oxide layer is significantly slower in HiPIMS than in dc sputtering under identical conditions. Further, we explain very high discharge currents in HiPIMS by the formation of truly stoichiometric compound during the discharge off-time. The compound has very high secondary electron emission coefficient and leads to a large increase in the discharge current upon target poisoning. Journal of Applied Physics

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“…An increased voltage for a constant current leads to a higher average powers. Since a pulsed voltage is used another phenomenon also arises when oxygen is added to the sputtering process of titanium, and that is that the peak current value increases for a constant average current [26].…”

Section: Reactive Sputteringmentioning

confidence: 99%

Titanium oxide nanoparticle production using high power pulsed plasmas

Gunnarsson¹

2016

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This thesis covers fundamental aspects of process control when growing titanium oxide nanoparticles in a reactive sputtering process. It covers the influence of oxygen containing gas on the oxidation state of the cathode from which the growth material is ejected, as well as its influence on the particles oxidation state and their nucleation. It was found that a low degree of reactive gases was necessary for nanoparticles of titanium to nucleate. When the oxygen gas was slightly increased, the nanoparticle yield and particle oxygen content increased. A further increase caused a decrease in particle yield which was attributed to a slight oxidation of the cathode. By varying the oxygen flow to the process, it was possible to control the oxygen content of the nanoparticles without fully oxidizing the cathode. Because oxygen containing gases such as residual water vapour has a profound influence on nanoparticle yield and composition, the deposition source was re-engineered to allow for cleaner and thus more stable synthesis conditions. The size of the nanoparticles has been controlled by two means. The first is to change electrical potentials around the growth zone, which allows for nanoparticle size control in the order of 25-75 nm. This size control does not influence the oxygen content of the nanoparticles. The second means of size control investigated was by increasing the pressure. By doing this, the particle size can be increased from 50 -250 nm, however the oxygen content also increases with pressure. Different particle morphologies were found by changing the pressure. At low pressures, mostly spherical particles with weak facets were produced. As the pressure increased, the particles got a cubic shape. At higher pressures the cubic particles started to get a fractured surface. At the highest pressure investigated, the fractured surface became poly-crystalline, giving a cauliflower shaped morphology.

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Understanding the discharge current behavior in reactive high power impulse magnetron sputtering of oxides

Cited by 94 publications

References 32 publications

Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

Evolution of sputtering target surface composition in reactive high power impulse magnetron sputtering

Titanium oxide nanoparticle production using high power pulsed plasmas

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